Charger Forums banner

1 - 6 of 6 Posts

·
Registered
Joined
·
6,124 Posts
Discussion Starter #1
Hey guys,

Just got back from doing my first ever datalog to see where im at

Im running the 93CAI tune with fans adjusted, shift firmness increased, MDS and EGR off........it was 95 degrees out today when I did this log.......PIDs logged are: knk LT retard, knk ST retard, Base spark, actual spark cyl 1, engine rpm, and accelerator pdl pos.........I logged a few WOT runs and short bursts here and there as well as some basic crusing.....problem is, I have no idea what to make of the data............
I got the log file saved but can someone who knows this stuff PLEASE tell me how to load the file on here, and review it for me :beerchug:

I do know I got 0 LT knock and a max of 4 degrees ST knock on WOT right after the shifts I believe
 

·
Registered
Joined
·
14,728 Posts
Hey guys,

Just got back from doing my first ever datalog to see where im at

Im running the 93CAI tune with fans adjusted, shift firmness increased, MDS and EGR off........it was 95 degrees out today when I did this log.......PIDs logged are: knk LT retard, knk ST retard, Base spark, actual spark cyl 1, engine rpm, and accelerator pdl pos.........I logged a few WOT runs and short bursts here and there as well as some basic crusing.....problem is, I have no idea what to make of the data............
I got the log file saved but can someone who knows this stuff PLEASE tell me how to load the file on here, and review it for me :beerchug:

I do know I got 0 LT knock and a max of 4 degrees ST knock on WOT right after the shifts I believe
you need to log more parameters than that.
you need lngfuel trim
pratio
avg pratio
tps (app is just the inside pedal and means little compared to what the throttle blade actually does)
more than 1 cyl of spark would be nice


long term fuel trim gives more info then knk in my opinion. all you basically logged for is knock in that situation which you know your good on. If you want to know if the fuel system is keeping up or not (which with your mods is about all that matters) you need long term in there too and pratio.
Egr should be on but whatever floats your boat there. it will do nothing to hamper you and will only increase gas mileage so why not?
 

·
Premium Member
Joined
·
7,632 Posts
you need to log more parameters than that.
you need lngfuel trim
pratio
avg pratio
tps (app is just the inside pedal and means little compared to what the throttle blade actually does)
more than 1 cyl of spark would be nice


long term fuel trim gives more info then knk in my opinion. all you basically logged for is knock in that situation which you know your good on. If you want to know if the fuel system is keeping up or not (which with your mods is about all that matters) you need long term in there too and pratio.
Egr should be on but whatever floats your boat there. it will do nothing to hamper you and will only increase gas mileage so why not?
I also like to recommend ECT (engine coolant temp), ACT (air charge temp), and MPH.

Is it necessary to log more than 1 cyl of spark? Shouldn't they always be the same, or would you be looking to find out if there's a problem with spark (misfire)? I would think that spark problems would set a CEL.

Without training everyone here to be a tuner, what would you recommend looking for in the long term fuel trim that would be useful in making adjustments on the handheld? I can totally understand if you're going to use your logs to get a full CMR tune so they can adjust cruising parameters, too, but don't the trims have very little to do with WOT operation?
 

·
Registered
Joined
·
14,728 Posts
I also like to recommend ECT (engine coolant temp), ACT (air charge temp), and MPH.

Is it necessary to log more than 1 cyl of spark? Shouldn't they always be the same, or would you be looking to find out if there's a problem with spark (misfire)? I would think that spark problems would set a CEL.

thats exactly it. Doing 1 cylinder tells you very little and every car is so different. Doing multiple allows you to compare them to each other and see which one, if any is having any issues. For example if you have 15 degrees on cyl 1 and no other readings what does that mean? but if you have 15 degrees on 7 cylinders and 2 degrees on 1 that would lead you to look into that cylinder more when problems arise. it helps to show a variance not only from cylinder to cylinder but bank to bank where things can be completely different. Remember a cel only sets if you are doing something harmful to emissions. You can have things hampering performance that will never set a light. the cel is only there specifically because the epa mandates it. A light on means you are polluting more than normal and a flashing light means you are polluting 1.5x the safe amount (this normally happens with a severe misfire or open injector) If the car can make subtle changes to one cylinder to keep it equal wouldnt the driver still want to know that that cylinder is taking more to fire at the rate of the others?

Without training everyone here to be a tuner, what would you recommend looking for in the long term fuel trim that would be useful in making adjustments on the handheld? I can totally understand if you're going to use your logs to get a full CMR tune so they can adjust cruising parameters, too, but don't the trims have very little to do with WOT operation?
Long term is the biggest thing "non tuners" should be looking at in my opinion.
For those that dont know long term is a fuel ratio. It goes from -25%-+25% and it is a fuel correction for your car.
example a
say a ford truck with 60k comes in on it and fuel trim is at +20%. that tells me the tech that the vehicle is dumping fuel like crazy to over come something. This can mean its overcoming a vacuum leak that is sending un metered air into the engine, or its overcoming a non changed fuel filter, maybe its overcoming a low injector , or its overccoming a bad pump. The programming of the computer allows for adjustments so that many things can be covered up. It can even add crazy amounts of fuel in the event someone is running ethanol blend which runs like crap at a lower btu rate and thus takes more fuel to operate under normal conditions. Hence why 10% ethanol blended fuel normally gets you 5% less mpg. In order to keep the car running due to part failure and owner neglect the pcm adapts many many things.


Now the opposite. Say the pcm is taking 15% fuel away (-15%). this could be due to a stuck open injector or low vacuum, or a misfire. Several things.

Ideally you want long term at or near 0 but variances are common for many reasons.

Short term is the opposite. short term is very very brief. If you mash the throttle you'll get + fuel which is the pcm adding fuel by way of injector on time, pulsewidth , or fuel pressure. Once short term ramps up too much (about 25%) it then kicks long term up 1 % and short term drops back to 0 . make sense? These numbers are different by manufacture but basically 25 shrt term is 1 long term



Now for those of us on the forum who mod our cars what does this mean?

two things.

a/ fuel really can only be tampered with in 3 rpm blocks by us. Cmr guys can do several almost hundreds (basically by like 50rpm increments where we can only do say 1-2500k, 2501k-4k, 4k-6k)
Now if your on the dyno and you drop from 12.5 a/f to 11 % at 4k then ya, you'd add 1% fuel to the 4k block and see if that gets you close to 12.5 across the board.

b/ long term. Say sublime has a cai, exhaust, cam, heads, and ported intake (for example only)
These are all air flow mods and nothing has been changed to the fuel system. Now if he's got long term at all rpm ranges in the 20% area what does that mean? It means the pcm is keeping the injectors on a lot more than normal and close to 25% all the time it will be maxed out (or 19ms ish if you have better scan tools that can log pulsewidth of the injector)
he would then know its time to bump the injectors to srt level or get a booster fuel pump or at the least some high flow rails. None the less he would know the pcm is covering up for a low fuel issue due to the air only mods and the fuel system needs help .


^^^^^^^^^^ that is very basic for shortness as most people dont read posts with more than 2 sentences in them anyway but hopefully its clear as mud and makes sense to someone.

or you can pull fuses and wipe out everything and have the car run like camel spit. :grin: its up to you
 

·
Premium Member
Joined
·
7,632 Posts
Thanks for the info. I guess I'll be adding some more PIDs to some of my logs.

or you can pull fuses and wipe out everything and have the car run like camel spit. :grin: its up to you
I found a station near me that sells 100 octane camel spit so I just might pull some fuses and fill her up there. ;)
 

·
Registered
Joined
·
1,184 Posts
Great info wickedchargerrt. Thanks for passing that along.
 
1 - 6 of 6 Posts
Top